A soccer ball, also referred to as a football, is the primary article of equipment used in the game of soccer. The traditional soccer ball conventionally includes a paneled casing that surrounds an inflatable bladder. The casing is formed of a plurality of durable, wear-resistant panels that are stitched together along abutting edges to form a closed surface. The bladder is located on the interior of the casing and formed of a material that is substantially impermeable to air. The bladder also includes a valved opening, accessible through the casing, to facilitate inflation. When inflated, the bladder expands and places an outward pressure upon the casing, thereby inducing the casing to take a substantially spherical shape, but not necessarily a perfectly spherical shape. Some soccer balls may also include a lining, which may include foam or a textile, between the bladder and the casing.
In mathematical terms, the panels that form the casing of the traditional soccer ball correspond to the various faces of a regular, truncated icosahedron. An icosahedron is a polyhedron having twenty faces. The term regular, when applied to an icosahedron, denotes a configuration wherein each of the twenty faces is an equally-dimensioned, equilateral triangle. A regular icosahedron, therefore, includes twenty equilateral triangular faces and twelve vertices that are formed where points of five triangular faces meet. A regular, truncated icosahedron is a regular icosahedron, as described, wherein each of the twelve vertices are removed (i.e., truncated) to form a pentagonal face. The remaining portions of the original twenty faces become equilateral hexagons. Accordingly, a regular, truncated icosahedron is a polyhedron having thirty-two faces, twelve of which are equilateral pentagons and twenty of which are equilateral hexagons, and sixty vertices formed where the points of three faces meet.
The traditional soccer ball casing is modeled on the regular, truncated icosahedron and includes thirty-two panels: twenty equilateral hexagonal panels and twelve equilateral pentagonal panels. The panels are stitched together along abutting edges. The internal pressure imparted by the bladder causes each panel of the traditional soccer ball to bow outward, thereby inducing a substantially, but not perfectly, spherical shape in the soccer ball. When the bladder is inflated, the area of contact between the bladder and casing is greater for the hexagonal panels than the pentagonal panels. This difference leads to the hexagonal panels bearing more stress from the bladder and may result in non-uniform deformation characteristics for the casing. Whether the ball is struck on a hexagonal panel or a pentagonal panel can, therefore, affect the subsequent path and velocity of the soccer ball. The difference in stress described above may also result in uneven wear between the hexagonal panels and the pentagonal panels. Also, the seams between the hexagonal panels may bear greater stress than the seams between hexagonal and pentagonal panels.